Increased motion of air and/or fuel charge injected into an engine combustion chamber can increase combustion efficiency under some conditions. For example, charge motion can increase the effectiveness of combustion by introducing air velocity and turbulence in directions perpendicular to the flow direction. By introducing additional kinetic energy into the combustion chambers, an ignition front may traverse the volume of the combustion chamber more quickly and more evenly so as to interact with a heightened amount of fuel before thermal energy is translated to piston motion. Further, resulting turbulence may increase homogenization of the air-to-fuel mixture within the combustion chamber as well as increase the burn rate, which is the time required to for the air/fuel mixture to burn completely during the combustion process.
To improve charge tumble and swirl parameters, various motion control devices may be coupled upstream of the intake of engine cylinders. By varying the charge motion of a cylinder, the cylinder burn rate can be varied. One example motion control device is shown by Overbeck in U.S. Pat. No. 4,928,638. Therein, an individual variable bladder is placed within an engine intake runner. The bladder may be configured to have a variable cross-section, the cross-section varied based on engine operating parameters. Specifically, a degree of inflation of the bladder is adjusted to vary the degree of occlusion of the flow path available for an air-fuel mixture entering the intake manifold.
However, the inventors herein have recognized potential issues with such devices. As one example, the location of the variable bladder inside the intake manifold (but upstream of individual intake runner s) may result in less than optimum charge mixing. While charge mixing may be improved by generating tumble and swirl downstream of the port runners, such a position is too close to the cylinder head. In addition to being spatially constrained, the bladder may be prone to thermal degradation at that position. Further, proximity to the hot cylinder head may affect the ability to control the amount of inflation/deflation achieved. For example, bladder heating may result in more inflation than desired. As such, this may adversely affect a combustion air-fuel ratio control. As another example, the bladder of Overbeck affects the charge motion to all cylinders globally but may not be able to adjust the charge motion of each cylinder individually. As such, there may be conditions where certain cylinders demand more or less charge motion than other cylinders.
In one example, the issues described above may be at least partly addressed by a system comprising a cylinder with an intake runner and a bladder positioned in an opening on a bottom surface of the intake runner nearest the cylinder. In this way, individual cylinder combustion may be improved by providing charge motion to each cylinder at a location inside port runners and closer to the cylinder head.
As an example, a variable cross section bladder may be coupled to a cartridge that is insertable into an engine bulkhead at a location proximate to the cylinder head where individual intake ports deliver air into corresponding cylinders. The bulkhead may be in fluid communication with a coolant passage(s) configured to circulate coolant. The cartridge may include an internal air passage sealed from the coolant by an extension member, the internal air passage delivering air to the bladder for varying an amount of bladder inflation. Based on engine operating conditions, such as air intake throttle position, an amount of air delivered to individual cartridge bladders may be varied. In this way, the bladder may be positioned in the small space available in the vicinity of the cylinder head. By coupling the variable bladder in a cylinder intake port of each cylinder of the engine, the tumble effect generated by the bladder upon inflation is improved. At the same time, by positioning the cartridge adjacent to a coolant passage of the cylinder wall, thermal degradation of the bladder is averted. In addition, the inflation/deflation of the bladder may be controlled more accurately despite the proximity to hot engine components.
The inventors have recognized that the above approach may provide various advantages. As one example, by using one or more of the example embodiments described above, alteration of individual cylinder intake air amounts may be permitted based on existing engine operating parameter(s). Another advantage is that the bladder may be easily installed and removed through the use of the cartridge. For example, the cartridge may comprise one or more variable bladders. The cartridge may be inserted into an opening of a bulkhead between an engine cylinder and an intake runner, wherein the cartridge extends through a portion of a space within the bulkhead. An engine coolant may flood the space within the bulkhead, thereby surrounding the cartridge with coolant. A bladder manifold may be fastened to an exterior of the cartridge in between the engine cylinder and an air intake manifold. In this way, the bladder manifold and cartridge may be compact and may conserve engine space. An advantage is that the bladder increases fuel economy by improving an air/fuel mixture and ultimately, improving a combustion efficiency.
The above discussion includes recognitions made by the inventors and not admitted to be generally known. Thus, it should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.